I would recommend checking the lens firmware version. The most recent version is 1.2 (1/25/2012). Mine seems good on the GH-4.

Have you tried using the 100-300mm in AF-C mode? Can you get an FPS rate over 4fps in AF-C mode (1) with the lens wide opened and (2) stopped down to, say, f/8?

Different users seem to get different results with this lens on the GH4 and E-M1 and I am trying to collect information.

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Chris R

I have used and tested 100-300mm with GH4. I can get 3-4 fps at f5.6 and it slows down gradually when stopping down. Fps is not constant, sometimes if subject moves very little the objective speeds up a little and if there is difficult movement the lens slows down.

I have found in sports events the best combination is f 6.3, iso 250-320 and shutter about 1250-1600. it needs a lot of light, there must be some sunshine. It it is cloudy I must rise iso.

Thank you for the information. Your results seem to be consistent with other GH4 users. The results on the E-M1 seem to be more variable.